The high balance-of-system costs of photovoltaic (PV) installations indicate that reductions in cell costs per watt alone are likely insufficient for PV electricity to reach grid parity unless energy conversion efficiency is also increased. Technologies that yield high-efficiency cells (e.g., greater than 25%) and maintain low costs are needed. GaAs and related III-V semiconductors are used in the highest-efficiency, single- and multi-junction photovoltaics, but the technology is too expensive for non-concentrated terrestrial applications. This expense is due in part to the inability to modify conventional methods, such as metal-organic chemical vapor deposition (MOCVD), in a manner that can produce commercial/industrial scale products at a low cost. MOCVD uses expensive reactors and uses toxic and pyrophoric gas-phase precursors such as arsine and trimethyl gallium, respectively. There exists a need in the art for methods and devices for making GaAs films having desired electronic properties in a scalable and cost efficient manner.